So, for the last couple days, I have been getting a white screen of death in the Customizer. The HHVM log is reporting this fatal error:
Uncaught exception 'BadMethodCallException' with message 'Call to a member function is_theme_active() on a non-object (NULL)' in /var/www/mydomain.com/wp-admin/customize.php:88\nStack trace:\n#0 {main}
I do not think I have changed anything (plugins, themes, server config) since it was last working except for possibly the upgrade to WP 4.2 / WP 4.2.1 (I don't specifically remember it working since that upgrade, but I may not have entered the customizer since that upgrade). I am running a multisite installation and I get the same results on all of my sites for both super admins as well as site admins. The customizer gives a white screen with a 500 (hphp_invoke) error in the browser console.
Any ideas on how I can go about debugging this further? Thanks!